Hi,
For passthrough device with intel_iommu.x-flts=on, we don't do shadowing of
guest page table but pass first stage page table to host side to construct a
nested HWPT. There was some effort to enable this feature in old days, see
[1] for details.
The key design is to utilize the dual-stage IOMMU translation (also known as
IOMMU nested translation) capability in host IOMMU. As the below diagram shows,
guest I/O page table pointer in GPA (guest physical address) is passed to host
and be used to perform the first stage address translation. Along with it,
modifications to present mappings in the guest I/O page table should be followed
with an IOTLB invalidation.
.-------------. .---------------------------.
| vIOMMU | | Guest I/O page table |
| | '---------------------------'
.----------------/
| PASID Entry |--- PASID cache flush --+
'-------------' |
| | V
| | I/O page table pointer in GPA
'-------------'
Guest
------| Shadow |---------------------------|--------
v v v
Host
.-------------. .-----------------------------.
| pIOMMU | | First stage for GIOVA->GPA |
| | '-----------------------------'
.----------------/ |
| PASID Entry | V (Nested xlate)
'----------------\.--------------------------------------------.
| | | Second stage for GPA->HPA, unmanaged domain|
| | '--------------------------------------------'
'-------------'
<Intel VT-d Nested translation>
This series reuse VFIO device's default HWPT as nesting parent instead of
creating new one. This way avoids duplicate code of a new memory listener,
all existing feature from VFIO listener can be shared, e.g., ram discard,
dirty tracking, etc. Two limitations are: 1) not supporting VFIO device
under a PCI bridge with emulated device, because emulated device wants
IOMMU AS and VFIO device stick to system AS; 2) not supporting kexec or
reboot from "intel_iommu=on,sm_on" to "intel_iommu=on,sm_off" on platform
with ERRATA_772415_SPR17, because VFIO device's default HWPT is created
with NEST_PARENT flag, kernel inhibit RO mappings when switch to shadow
mode.
This series is also a prerequisite work for vSVA, i.e. Sharing guest
application address space with passthrough devices.
There are some interactions between VFIO and vIOMMU
* vIOMMU registers PCIIOMMUOps [set|unset]_iommu_device to PCI
subsystem. VFIO calls them to register/unregister HostIOMMUDevice
instance to vIOMMU at vfio device realize stage.
* vIOMMU registers PCIIOMMUOps get_viommu_flags to PCI subsystem.
VFIO calls it to get vIOMMU exposed flags.
* vIOMMU calls HostIOMMUDeviceIOMMUFD interface [at|de]tach_hwpt
to bind/unbind device to IOMMUFD backed domains, either nested
domain or not.
See below diagram:
VFIO Device Intel IOMMU
.-----------------. .-------------------.
| | | |
| .---------|PCIIOMMUOps |.-------------. |
| | IOMMUFD |(set/unset_iommu_device) || Host IOMMU | |
| | Device |------------------------>|| Device list | |
| .---------|(get_viommu_flags) |.-------------. |
| | | | |
| | | V |
| .---------| HostIOMMUDeviceIOMMUFD | .-------------. |
| | IOMMUFD | (attach_hwpt)| | Host IOMMU | |
| | link |<------------------------| | Device | |
| .---------| (detach_hwpt)| .-------------. |
| | | | |
| | | ... |
.-----------------. .-------------------.
Below is an example to enable first stage translation for passthrough device:
-M q35,...
-device intel-iommu,x-scalable-mode=on,x-flts=on...
-object iommufd,id=iommufd0 -device vfio-pci,iommufd=iommufd0,...
Test done:
- VFIO devices hotplug/unplug
- different VFIO devices linked to different iommufds
- vhost net device ping test
- migration with QAT passthrough
PATCH01-08: Some preparing work
PATCH09-10: Compatibility check between vIOMMU and Host IOMMU
PATCH11-16: Implement first stage translation for passthrough device
PATCH17-18: Add migration support and optimization
PATCH19-21: Workaround for ERRATA_772415_SPR17
PATCH22: Enable first stage translation for passthrough device
PATCH23: Add doc
Qemu code can be found at [2], it's based on
vfio-next + migration_relax_series[3].
Fault event injection to guest isn't supported in this series, we presume guest
kernel always construct correct first stage page table for passthrough device.
For emulated devices, the emulation code already provided first stage fault
injection.
TODO:
- Fault event injection to guest when HW first stage page table faults
[1]
https://patchwork.kernel.org/project/kvm/cover/[email protected]/
[2] https://github.com/yiliu1765/qemu/tree/zhenzhong/iommufd_nesting.v8
[3]
https://lore.kernel.org/qemu-devel/[email protected]/
Thanks
Zhenzhong
Changelog:
v8:
- add hw/i386/intel_iommu_accel.[hc] to hold accel code (Eric)
- return bool for all vtd accel related functions (Cedric, Eric)
- introduce a new PCIIOMMUOps::get_host_iommu_quirks() (Eric, Nicolin)
- minor polishment to comment and code (Cedric, Eric)
- drop some R-b as they have changes needing review again
v7:
- s/host_iommu_extract_vendor_caps/host_iommu_extract_quirks (Nicolin)
- s/RID_PASID/PASID_0 (Eric)
- drop rid2pasid check in vtd_do_iommu_translate (Eric)
- refine DID check in vtd_pasid_cache_sync_locked (Liuyi)
- refine commit log (Nicolin, Eric, Liuyi)
- Fix doc build (Cedric)
- add migration support
v6:
- delete RPS capability related supporting code (Eric, Yi)
- use terminology 'first/second stage' to replace 'first/second level" (Eric,
Yi)
- use get_viommu_flags() instead of get_viommu_caps() (Nicolin)
- drop non-RID_PASID related code and simplify pasid invalidation handling
(Eric, Yi)
- drop the patch that handle pasid replay when context invalidation (Eric)
- move vendor specific cap check from VFIO core to backend/iommufd.c (Nicolin)
v5:
- refine commit log of patch2 (Cedric, Nicolin)
- introduce helper vfio_pci_from_vfio_device() (Cedric)
- introduce helper vfio_device_viommu_get_nested() (Cedric)
- pass 'bool bypass_ro' argument to vfio_listener_valid_section() instead of
'VFIOContainerBase *' (Cedric)
- fix a potential build error reported by Jim Shu
v4:
- s/VIOMMU_CAP_STAGE1/VIOMMU_CAP_HW_NESTED (Eric, Nicolin, Donald, Shameer)
- clarify get_viommu_cap() return pure emulated caps and explain reason in
commit log (Eric)
- retrieve the ce only if vtd_as->pasid in vtd_as_to_iommu_pasid_locked (Eric)
- refine doc comment and commit log in patch10-11 (Eric)
v3:
- define enum type for VIOMMU_CAP_* (Eric)
- drop inline flag in the patch which uses the helper (Eric)
- use extract64 in new introduced MACRO (Eric)
- polish comments and fix typo error (Eric)
- split workaround patch for ERRATA_772415_SPR17 to two patches (Eric)
- optimize bind/unbind error path processing
v2:
- introduce get_viommu_cap() to get STAGE1 flag to create nesting parent HWPT
(Liuyi)
- reuse VFIO's default HWPT as parent HWPT of nested translation (Nicolin,
Liuyi)
- abandon support of VFIO device under pcie-to-pci bridge to simplify design
(Liuyi)
- bypass RO mapping in VFIO's default HWPT if ERRATA_772415_SPR17 (Liuyi)
- drop vtd_dev_to_context_entry optimization (Liuyi)
v1:
- simplify vendor specific checking in vtd_check_hiod (Cedric, Nicolin)
- rebase to master
Yi Liu (3):
intel_iommu_accel: Propagate PASID-based iotlb invalidation to host
intel_iommu: Replay all pasid bindings when either SRTP or TE bit is
changed
intel_iommu: Replay pasid bindings after context cache invalidation
Zhenzhong Duan (20):
intel_iommu: Rename vtd_ce_get_rid2pasid_entry to
vtd_ce_get_pasid_entry
intel_iommu: Delete RPS capability related supporting code
intel_iommu: Update terminology to match VTD spec
hw/pci: Export pci_device_get_iommu_bus_devfn() and return bool
hw/pci: Introduce pci_device_get_viommu_flags()
intel_iommu: Implement get_viommu_flags() callback
intel_iommu: Introduce a new structure VTDHostIOMMUDevice
vfio/iommufd: Force creating nesting parent HWPT
intel_iommu_accel: Check for compatibility with IOMMUFD backed device
when x-flts=on
intel_iommu_accel: Fail passthrough device under PCI bridge if
x-flts=on
intel_iommu_accel: Stick to system MR for IOMMUFD backed host device
when x-flts=on
intel_iommu: Add some macros and inline functions
intel_iommu_accel: Bind/unbind guest page table to host
vfio/listener: Bypass readonly region for dirty tracking
intel_iommu: Add migration support with x-flts=on
hw/pci: Introduce pci_device_get_host_iommu_quirks()
intel_iommu_accel: Implement get_host_iommu_quirks() callback
Workaround for ERRATA_772415_SPR17
intel_iommu: Enable host device when x-flts=on in scalable mode
docs/devel: Add IOMMUFD nesting documentation
MAINTAINERS | 2 +
docs/devel/vfio-iommufd.rst | 25 ++
hw/i386/intel_iommu_accel.h | 55 ++++
hw/i386/intel_iommu_internal.h | 155 ++++++---
include/hw/i386/intel_iommu.h | 5 +-
include/hw/iommu.h | 30 ++
include/hw/pci/pci.h | 55 ++++
include/hw/vfio/vfio-container.h | 1 +
include/hw/vfio/vfio-device.h | 5 +
hw/i386/intel_iommu.c | 530 ++++++++++++++++++-------------
hw/i386/intel_iommu_accel.c | 272 ++++++++++++++++
hw/pci/pci.c | 35 +-
hw/vfio/device.c | 26 ++
hw/vfio/iommufd.c | 18 +-
hw/vfio/listener.c | 48 ++-
tests/qtest/intel-iommu-test.c | 4 +-
hw/i386/Kconfig | 5 +
hw/i386/meson.build | 1 +
hw/i386/trace-events | 4 +
hw/vfio/trace-events | 1 +
20 files changed, 979 insertions(+), 298 deletions(-)
create mode 100644 hw/i386/intel_iommu_accel.h
create mode 100644 include/hw/iommu.h
create mode 100644 hw/i386/intel_iommu_accel.c
--
2.47.1
